A hybrid fiber-coaxial (HFC) network is a broadband network that combines optical fiber and coaxial cable. The HFC network typically provides two-way communication between a cable operator's headend facility and a subscriber's location. The headend facility collects and processes communication signals, and distributes the signals to the subscriber's location using a downstream communication path. Customer premises equipment (CPE), typically a set-top box, gateway, or cable modem, at the subscriber's location receives the communication signals on the downstream communication path, and transmits other communication signals to the headend facility using an upstream communication path.
The headend processes all of the upstream and downstream traffic in an HFC cable plant. Currently, the cable television industry in the United States utilizes a split spectrum allocation that has upstream channels at 5-42 MHz, and downstream channels at 54-1000 MHz. Currently, the cable television industry in the rest of the world utilizes a split stream allocation that has upstream channels at 5-65 MHz, and downstream channels at 88-860 MHz.
For several years, the cable television industry in the United States has considered moving the upstream/downstream spectrum split. Radio frequency over glass (RFoG), a telecommunications network design that replaces the coax portion of the HFC network with a single-fiber passive optical network (PON), can support an expended upstream spectrum split. In addition, the Data Over Cable Service Interface Specification (DOCSIS) 3.0 standard can support an upstream/downstream spectrum split at 85 MHz, and the DOCSIS 3.1 standard can support an upstream/downstream spectrum split at 200 MHz.